Adhoc
　Network Management of AD-HOC Networks 　　 1. Introduction A collection of communication devices (nodes) that wish to communicate with each other without any fixed communication infrastructure is known as an ad-hoc network 1. As a consequence of node mobility ad-hoc networks present rapid changes in node connectivity and link characterization, network management proves to be challenging .Different organizational models are used by different management approaches ,these models are shown in Figure 1 . 2. An SNMP Based Network Management Approach 2.1 Ad-hoc Network Management Protocol (ANMP) With SNMP as foundation, ANMP is a management protocol implemented for ad-hoc networks, using the centralized hierarchical management .Some highlighted features of ANMP are listed below.ANMP uses the same protocol data unit structure (PDU), Management Information Base (MIB) structure ,UDP is the transport protocol used for transporting ANMP messages. ANMP is a light weight version of SNMP which employs node clustering and hierarchical levels architecture. The management plane is divided into three levels of hierarchy, the lowest level of this architecture consists of individual managed nodes called agents. Several agents are grouped into clusters and are managed by a cluster head which in turn are managed by the network manager 3. ANMP defines a geographical based and a graphical based clustering algorithms , the geographical algorithm constructs up to three-hop clusters based on node spatial density and GPS positions , whereas the latter constructs on-hop clusters based on network topology. ] The aim of this hierarchical model is to reduce the network traffic overhead by organizing management data at the intermediate levels. Figure 3 depicts the anmpMib, defined specifically for MANET. ] ANMP implements the military security model, here security clearances are assigned to nodes and security classification is assigned to data. Nodes can read MIB data at security levels equal or lower than its own security level. The manager assigns security levels to all nodes, which is distributed to each cluster head and then to each cluster node. An example of this scenario is shown in Figure 4, higher numeric value depict lower levels of security. ] ] Security information is defined by the Level Based Access Control Model (LACM) and it is a part of the anmp MIB. 2.2 Guerrilla Management Architecture (GMA) ' ' GMA uses the distributed hierarchical management model and supports a peer to peer paradigm. Management is carried out in two levels, the higher level consists of a group of nomadic managers that adapt to network dynamics, collaborate with each other and serve as focal points for other neighboring nodes .The lower level consists of active probes (small programmable scripts), utilized for local management functions. GMA classifies nodes based on management ability. Nodes with least ability execute an SNMP agent, nodes with sufficient ability comprise of both a Probe processing module and an SNMP agent. Nodes with appropriate processing power and energy levels, undertake the roles of Nomadic manager and contains a Nomadic Management Module. ] Based on the network dynamics the node classification also changes .To minimize management traffic, nomadic managers sends active probes which navigate the network so as to perform localized management functions 4. Nodes are grouped into clusters, where each cluster has a nomadic manager .These managers cooperate among themselves to manage the whole network. 2. 2.2.3 Advantages/Disadvantages ''' The advantage of an SNMP based approach is that it performs complex management task, executes more precise management decisions and employs the use of SNMP, a well-established network management protocol. The cost of maintaining and constructing a hierarchy, high message overload and single point of failure does prove to be a disadvantage ]. '''3. SNMP based approach Vs. Other Management Paradigms Traditional SNMP and ANMP focus on individual devices in the network, which could become quite tedious when the network is large. A number of other approaches are present but not highlighted here, a comparative look based on FCAPS shown in Figure 8 ] References: 1 Ram Bamanathan and Jason Redi, A Brief Overview of Ad Hoc Network: Challenges and Directions, IEEE Communications Magazine, 50th Anniversary Commemorative Issue, May 2002 2 Handbook of Network and System Administration by Jan Bergstra Mark Burgess 3 W. Chen, N. Jain, S. Singh, “ANMP: Ad Hoc Network ManagementProtocol”, IEEE Journal on Selected Areas in Communications, June 1999 4 C. Shen, C. Jaikaeo, C. Srisathapornphat, and Z. Huang,The GUERRILLA Management Architecture for Ad-hocNetworks. (MILCOM’02), Anaheim, CA, USA, October2002